Concentric vertical duct propulsion for aircraft

Abstract

To provide an aircraft and a method for controlling the aircraft.SOLUTION: A system, method, and apparatus includes an aircraft (AV) having a plurality of coaxially arranged vertical ducts. The lower vertical duct has a larger diameter than the upper vertical duct. Further, the upper vertical duct at least partially has a first thrust component and the lower vertical duct at least partially has a second thrust component. The lower vertical duct can be joined to the upper vertical duct by a duct coupler that forms an intake gap between the upper vertical duct and the lower vertical duct. The AV also includes one or more steering flaps disposed in the lower vertical duct and configured to manipulate airflow directed into a bottom portion of the lower duct to control navigation and stability of the AV.SELECTED DRAWING: Figure 5A

Description

[Technical Field]

[0001] Aspects of the present disclosure relate to aircraft, such as manned aircraft or aircraft, having multiple vertical ducts or flow fields that provide efficient thrust, maneuverability, and payload placement within or on the aircraft body. [Background technology]

[0002] Aerial vehicles (AVs) perform a variety of tasks, including aerial surveillance for military, civil, and commercial purposes. Such AVs typically use multiple rotating, planar propellers to generate lift and control the AV's flight path. However, the use of multiple propellers can negatively impact the AV's overall efficiency by reducing flight time and lift capacity. For this reason, traditional AV configurations (such as four or more exposed propellers connected to a small center body) have limited payload volume and may be unsafe for operation around humans and / or animals due to the exposed propellers. Nevertheless, this configuration is being widely adopted in many new urban airlift aircraft designs, where efficiency, flight time, and payload volume should be paramount.

[0003] It is with these observations, among others, in mind that various aspects of the presently disclosed technology were conceived and developed. Summary of the Invention [Means for solving the problem]

[0004] The aforementioned problems can be addressed using systems, methods, and apparatus according to the present disclosure. For example, an aircraft may include a first duct defining at least a first portion of a lift-generating airpath; a second duct disposed below and collinear with the first duct and defining at least a second portion of the airpath; and one or more propellers or propulsion systems disposed within at least one of the first duct or the second duct and generating airflow through the airpath. The one or more propulsion devices may include propellers, rotors, turbomachinery components, or gas-fired jet components. In some configurations, one or more flaps are coupled to the second duct and movable between different positions to influence, deflect, or otherwise alter the airflow to control the movement of the aircraft.

[0005] Various configurations of the aircraft are possible. For example, some configurations may include a first duct extending into a second duct such that at least a portion of the first duct is located inside the second duct. In some examples, the first duct may have a first diameter, and the second duct may have a second diameter that is longer than the first diameter. In other examples, the first diameter of the first duct may be longer than the second diameter of the second duct. In still other examples, one or both of the propellers may operate in an open configuration without a duct, in which case the different sized propellers may rotate at different speeds to optimize the tip speed of each propeller.

[0006] The aircraft may also include one or more duct couplers connecting the first duct to the second duct. The one or more duct couplers may be hinged to allow the second duct to move relative to the first duct and, in some examples, may be used as a control mechanism and / or a method of collapsing the body to conserve space during storage. Additionally, the one or more propellers may include a first propeller disposed in the first duct and a second propeller disposed in the second duct. Further, the first propeller may have a first length dimension and the second propeller may have a second length dimension that is longer than the first length dimension.

[0007] In some examples, a propulsion mechanism (such as, but not limited to, a rotating propeller, a rotor, a turbomachinery component, a gas-fired jet, etc.) may be driven by one or more motors supported by connection to aerodynamically shaped struts, such as stators. Such stators may be configured to be aerodynamically neutral or near-neutral (e.g., including symmetrical shapes with zero or near-zero incoming flow) and may serve the purpose of redirecting or shaping the airflow. Such stators may be positioned above or below the propeller or other propulsion mechanism and may include any number of stators. In one particular example, the connected struts may be positioned downwind of the airflow to reduce noise generated by the aircraft. When located upwind of one or more propellers, the connected struts may be designed or configured to be neutral or to impart a given amount of turn.

[0008] In some examples, one or more motors may be installed within the duct volume and include drive shafts within stator blades that transfer power to the propulsion system. Additionally, stator blades or fins located below the bottom propeller may provide airflow compensation and / or additional protection against damage to the bottom propeller from external objects.

[0009] In some examples, the one or more flaps may include a plurality of flaps, such as four flaps spaced equidistantly around the exterior of the second duct. The second duct may also include a plurality of receiving areas formed on an exterior surface of the second duct to receive the plurality of flaps when the flaps are in the stowed position. Further, the aircraft may include an intake gap formed by a space between the first duct and the second duct.

[0010] In some examples, the aircraft includes a first duct defining at least a first portion of the airpath and / or a second duct defining at least a second portion of the airpath. The second duct can be aligned below and collinear with the first duct. The aircraft can also include one or more propellers disposed in the second duct that draw air through at least one intake gap defined between the first and second ducts and / or one or more movable navigation members coupled to the second duct for controlling movement of the aircraft.

[0011] In some scenarios, the one or more movable navigation elements may include at least one of a plurality of flaps movable between a retracted position and an extended position or a plurality of wheels deploying from the second duct. Furthermore, the aircraft may include a plurality of duct couplers extending between the first duct and the second duct. Additionally, the aircraft may include an intake gap having a width dimension corresponding to a length of the plurality of duct couplers. Furthermore, the one or more propellers may include a first propeller disposed in the first duct and / or a second propeller disposed in the second duct. The second propeller may be larger than the first propeller. The aircraft may also include a memory device storing computer-readable instructions that, when executed by the one or more processors, cause the aircraft to perform a maneuvering operation by extending at least one of the one or more movable navigation elements into the airpath.

[0012] In some examples, a method of controlling movement of an aircraft may include generating at least a first portion of lift for the aircraft by rotating a first propeller disposed in a first vertical duct, generating at least a second portion of lift by rotating a second propeller disposed in a second vertical duct below the first vertical duct and aligned coaxially with the first vertical duct, and / or varying airflow through an airpath defined by the first vertical duct aligned coaxially with the second vertical duct by movement of one or more flaps disposed in the second vertical duct.

[0013] In some examples, creating a change in the airflow may affect a lift component, and the aircraft may be maneuvered based on the change to the airflow affecting the lift component. The method may also include rotating the second propeller to draw air through an intake gap between the first vertical duct and the second vertical duct. The method may also include maneuvering one or more ducts such that the first vertical duct moves relative to the second vertical duct as part of the flight operation, thereby displacing a center of thrust and generating a moment. The thrust displacement may be in-plane or may include a tilt angle. The method may also further include actuating one or more duct couplers to collapse the aircraft into a storage mode.

[0014] In other implementations, several small propellers, perhaps each with a tilted axis, can be used to cover the secondary flow region without sharing or interacting with the airflow coming from the top duct. Flight control may be achieved by varying the rotation of each of the propellers. In one example, the interface between the two regions is separated by a wall whose cross-sectional shape along the vertical coordinate can be changed to cover the region between the small propellers and increase the total effective area.

[0015] Also, other implementations are described and enumerated. Moreover, while multiple implementations are disclosed, still other implementations of the disclosed technology will become apparent to those skilled in the art from the following detailed description, which shows and describes exemplary implementations of the disclosed technology. As will be understood, the disclosed technology can be modified in various aspects without departing from the spirit and scope of the disclosed technology. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. [Brief explanation of the drawings]

[0016] [Figure 1] (A) is a plan view showing a multicopter aircraft configuration, and (B) is a plan view showing a single propeller configuration. [Figure 2] (A) is a plan view showing a multicopter aircraft with a payload area above the propellers; (B) is a plan view showing a single propeller aircraft with a cylindrical payload area above the propellers; (C) is a cross-sectional view of an AV with four propellers and corresponding payload areas; and (D) is a cross-sectional view of an AV with a single propeller and corresponding payload area. [Figure 3] (A) is a cross-sectional view of an AV with four propellers and a corresponding streamlined payload area, and (B) is a cross-sectional view of an AV with a single propeller and a corresponding streamlined payload area. [Figure 4] (A) is a cross-sectional view of an AV configuration including an upper propeller oriented perpendicularly from the lower propeller and a corresponding payload area, and (B) is a cross-sectional view of an AV configuration with an upper propeller identical to the upper propeller shown in (A) and a lower propeller configured to cover only the area receiving airflow from the secondary intake area. [Figure 5A] FIG. 1 is a front view of an exemplary system including multiple collinear vertical ducts that may form at least a portion of an aircraft. [Figure 5B] FIG. 1 is a front perspective view of an exemplary system. [Figure 5C] FIG. 1 is a bottom view of an exemplary system including multiple collinear vertical ducts that may form at least a portion of an aircraft. [Figure 5D] FIG. 1 is a plan view of an exemplary system including multiple collinear vertical ducts that may form at least a portion of an aircraft. [Figure 5E] FIG. 1 is a left side view of an exemplary system including multiple collinear vertical ducts that may form at least a portion of an aircraft. [Figure 5F] FIG. 1 is a right side view of an exemplary system including multiple collinear vertical ducts that may form at least a portion of an aircraft. [Figure 5G] FIG. 1 is a rear view of an exemplary system including a plurality of collinear vertical ducts that may form at least a portion of an aircraft. [Figure 5H] FIG. 1 illustrates a bottom view of an exemplary system including one or more stators for controlling airflow through the system. [Figure 6A] FIG. 1 is a front view of an exemplary system including an aircraft having multiple collinear vertical ducts. [Figure 6B] FIG. 1 is a front perspective view of an exemplary system including an aircraft having multiple collinear vertical ducts; [Figure 6C] FIG. 1 is a bottom view of an exemplary system including an aircraft having collinear vertical ducts. [Figure 6D] FIG. 1 is a top view of an exemplary system including an aircraft having multiple collinear vertical ducts. [Figure 6E] FIG. 1 is a left side view of an exemplary system including an aircraft having collinear vertical ducts. [Figure 6F] FIG. 1 is a right side view of an exemplary system including an aircraft having collinear vertical ducts. [Figure 6G] FIG. 1 is a rear view of an exemplary system including an aircraft having multiple collinear vertical ducts. [Figure 7] FIG. 1 is a cross-sectional view of an aircraft configured such that the body walls generate a majority of the lift when the AV is in forward flight. [Figure 8] FIG. 1 is a side perspective view of an exemplary system including an aircraft having multiple collinear vertical ducts for performing maneuvers; [Figure 9] FIG. 1 is a block diagram of an exemplary method for controlling an aircraft having two collinear vertical ducts. [Figure 10] (A) is a cross-sectional view of an aircraft with a bottom propulsion system horizontally offset from the top propulsion system, and (B) is a cross-sectional view of an aircraft with a bottom propulsion system that is horizontally offset from the top propulsion system and angled relative to the top propulsion system. DETAILED DESCRIPTION OF THE INVENTION

[0017] Air vehicles (AVs), which may include unmanned or manned aircraft, typically use multiple rotating propellers to generate lift and control the AV's flight path. However, using multiple propellers in a conventional configuration (such as a quadcopter) is generally not the best approach for efficient use of space and energy storage. Therefore, flight time and lift capacity can be significantly reduced, since performance is inherently related to the area effectively used to drive thrust-directed flow. Typically, each propeller disk of an AV has an inefficient zone near the center of the propeller, and in a multicopter configuration, there is an additional dead zone between the propeller disks. For example, FIG. 1(A) is a plan view of a multicopter aircraft configuration 1000, and FIG. 1(B) is a plan view of a single-propeller configuration 1020. As shown in FIG. 1(A), an outer ring 1002 represents the available footprint of the aircraft, which in this example is assumed to be a disk of a given radius R. Each propeller 1004 is represented by a smaller ring with radius r. To operate the aircraft, each propeller 1004 drives an airflow downward, creating aerodynamic lift. For illustrative purposes, it is assumed that there is a dead zone (represented by the central ring 1006) for each of the disk propellers with a radius d of 0.1r. To fit four propellers into the available area of ​​the aircraft footprint 1002, the maximum value of r is approximately r = 0.41R. After subtracting the four central dead zones 1006 for each of the propellers 1004, the airflow area of ​​the configuration is 4π (0.17R2 -d 2 ), which is less than 70% of the total available footprint area 1002. In terms of the energy or power required to operate the aircraft, this represents approximately 20% more power required for the propeller shown in FIG. 1(B) than for a configuration that covers the entire footprint area 1002.

[0018] Another source of efficiency loss is payload volume, which is typically located downwind and upwind of the propeller, causing some degree of airflow blockage, turbulence, and drag. For example, FIG. 2(A) is a plan view of a multicopter aircraft with a payload area above the propeller, and FIG. 2(B) is a plan view of a single-propeller aircraft with a payload area above the propeller. The multicopter 2000 in FIG. 2(A) includes a configuration similar to the AV in FIG. 1(A) and has a payload area 2006. Similarly, the single-propeller AV 2010 in FIG. 2(B) is similar to the previously described single-propeller AV 2010 in FIG. 1(B) and has a payload area 2006. Note that the two payloads have different cylindrical cross sections (rectangular in FIG. 2(A) and circular in FIG. 2(B)). FIG. 2(C) is a cross-sectional view of an AV 2020 having four propellers and corresponding payload area 2006 (two visible in FIG. 2(C) and two hidden), and FIG. 2(D) is a cross-sectional view of an AV 2030 having a single propeller and corresponding payload area 2006. Each of FIGS. 2(C) and 2(D) shows the airflow generated by the propellers around the corresponding payload 2006. As shown, the payload volume of an AV can cause a certain amount of blockage, turbulence, and drag. For this reason, conventional AV configurations in which four or more exposed propellers are connected to a small center body are generally large to accommodate the payload because the volumetric space for the payload is limited, and are generally unsafe for operation around humans and animals. An alternative configuration (using a single propeller to fit within the footprint area) uses the available area more efficiently, yet suffers from significant payload blockage, as shown in FIGS. 2(B) and 2(D).

[0019] In some instances, the payload volumes shown in Figures 2(A)-2(D) may be optimized to mitigate turbulence and blockage by streamlining the body, but typically involve elongated shapes that dramatically increase the overall dimensions of the device. This applies to both the multicopter and single-propeller AV configurations described above. For example, Figure 3(A) is a cross-sectional view of an AV 3000 having four propellers (such as the four propellers shown in Figure 2(A)) and a corresponding streamlined payload area 3006, while Figure 3(B) is a cross-sectional view of an AV 3010 having a single propeller and a corresponding streamlined payload area 3006. While the streamlined payload area 3006 reduces turbulence and blockage of the airflow over the propellers, the payload area itself dramatically increases the size and weight of the aircraft, reducing the overall performance of the AV.

[0020] Thus, this specification discloses an AV design that improves efficiency through increased payload volume, and, given a set of dimensional constraints, enables an AV with significantly improved safety, flight time, and overall performance.

[0021] The improvements to conventional AV configurations introduced herein dramatically improve overall efficiency by effectively utilizing the AV's outlet area, but counter to common intuition, by noting that the incoming flow may be vertical or lateral. This concept allows for more effective use of the AV's available area by supplying different areas of the outlet area with incoming airflow from different inlets in different directions. As a simple example, FIG. 4(A) is a cross-sectional view of an AV configuration 4000 including an upper propeller 4002 oriented perpendicularly from a lower propeller 4004. The orientation and configuration of the propellers 4002 and 4004 of the AV 4000 will be described in more detail. FIG. 4(A) illustrates the airflow through the propellers of the AV configuration and the corresponding payload area 4006. In particular, more efficient airflow is achieved by supplying different areas of the outlet area with airflow coming from different inlets from different directions. Furthermore, the illustrated configuration allows for the design of a streamlined payload volume 4006, which significantly improves upon conventional AV configurations with the goal of providing useful volume and weight payload for given configuration constraints, along with optimal efficiency and flight time. In particular, new airflow from various directions captured from secondary (i.e., side) inlets can be used to drive flow in turbulence / separation-prone regions, dividing the exiting flow region into two or more sections, allowing for larger and shorter payload shapes. Additionally, low noise characteristics can be achieved by minimizing interference between the propellers, with each propeller driving the flow in a given region independently of the other propellers. Another advantage of having two or more ducts is that each corresponding propeller, rotor, or propulsion system operates at a different optimal speed. For example, a larger propeller (typically the bottom-most propeller) will operate at a lower rpm (revolutions per minute) than a smaller propeller (typically the top propeller driving the innermost flow region), allowing the propellers to operate at similar tip speeds.

[0022] These benefits can be achieved in various ways, such as by designing the full center section of the bottom propeller 4004 (as shown in FIG. 4(A)) to be aerodynamically neutral (zero inflow and symmetrical), receiving the flow from the upper propeller 4002. In another implementation of the AV 4010, shown in FIG. 4(B), the lower propeller 4014 is configured to cover only the area receiving airflow from the secondary (i.e., side) inflow area. In this case, the rotor of the lower propeller 4014 may have blades only in the annular area that spans the area where airflow comes from the side intakes. The independence of the two (or more) areas also benefits overall efficiency. With the configurations shown in FIGS. 4(A) and 4(B) and given spatial constraints, increased flow area (perhaps greater than 98% compared to less than 70% for a typical quad-propeller AV), energy or power efficiency, flight time, and maximum payload volume in a compact area can be achieved.

[0023] The disclosed systems, methods, and apparatus include an air vehicle (AV) having multiple (e.g., two) coaxially arranged vertical ducts, which may be generally axisymmetric or cylindrical. The described systems and methods are generally applicable to both unmanned and manned aircraft. The AV may include one or more steering flaps disposed in the lower duct and configured to manipulate airflow directed into the bottom of the lower duct to control the AV's navigation and stability. The lower duct may be coupled to the upper duct by a duct coupler that forms an intake gap between the upper and lower ducts. Furthermore, the lower duct may have a larger diameter than the upper duct and a correspondingly larger propeller.

[0024] In some scenarios, this configuration of components improves efficiency and increases the flight time and payload capacity of the AV. The upper and / or lower ducts can also have housings that provide space for various components (such as batteries, control systems, sensors, and cargo), improving the weight distribution of the AV. Furthermore, a larger lower duct and / or an intake gap between multiple ducts can be used to prevent flow separation at the top surface of the body, allowing for optimal use of available volume. In this way, one or more intake gaps, as opposed to a single continuous duct, can help create a more uniform airflow through the AV, reducing pitch-up motion during forward flight and reducing airflow separation from the duct walls. This configuration also allows for a compact payload volume that is large and aerodynamically efficient in preventing airflow separation and excessive turbulence. Another advantage is that both ducts can be used to provide additional lift when the AV is maneuvered at smaller angles (relative to horizontal), such as in an annular wing configuration. Additional configurations may include an outermost surface of the bottom duct configured to passively generate opposing, corrective momentum in response to sudden wind gusts. For example, the bottom of the bottom duct may have an annular multi-element profile with an annular axisymmetric arrangement. When a wind gust reaches this portion of the bottom duct, the flow accelerates within one or more channels, creating a strong pressure differential that generates aerodynamic forces that counteract the wind momentum. Additional benefits and advantages of the disclosed techniques will become apparent from the detailed description below.

[0025] 5A-5G illustrate an exemplary system 100 including an aircraft (AV) 102 equipped with a first vertical duct 104 and / or a second vertical duct 106 that can be coaxially aligned with the first vertical duct 104. Figure 5A is a front view of the first vertical duct 104 and the second vertical duct 106 of the AV 102, Figure 5B is a front perspective view of the first vertical duct 104 and the second vertical duct of the AV 102, Figure 5C is a bottom view of the first vertical duct 104 and the second vertical duct of the AV 102, Figure 5D is a plan view of the first vertical duct 104 and the second vertical duct of the AV 102, Figure 5E is a left side view of the first vertical duct 104 and the second vertical duct of the AV 102, Figure 5F is a right side view of the first vertical duct 104 and the second vertical duct of the AV 102, and Figure 5G is a rear view of the first vertical duct 104 and the second vertical duct of the AV 102. Although the examples described and discussed refer to two ducts, it will be understood that any number may be included that allows flexibility in optimizing the operating rotational speed of the rotor or propeller.

[0026] In some examples, the first vertical duct 104 may be an upper duct forming an upper portion of the AV 102, and the second vertical duct 106 may be a bottom duct forming a lower portion of the AV 102. One or more duct couplers 108 may couple the first vertical duct 104 to the second vertical duct 106. For example, the one or more duct couplers 108 may include an arm, beam, or other intermediate member attached to and extending from the bottom (e.g., bottom edge 110) of the first vertical duct 104 and attached to the top (e.g., top edge 112) of the second vertical duct 106. The AV 102 may include any number of duct couplers 108, such as two, three, four, five, six, and so on. Duct couplers may also be utilized to route wires and / or connect components located in a second duct to a first duct housing other electronic components.

[0027] Additionally, the duct coupler 108 may space the first vertical duct 104 from the second vertical duct 106 to define an intake gap 114 between the first vertical duct 104 and the second vertical duct 106. The intake gap 114 may have a width dimension 116 that corresponds to a length dimension 118 of the one or more duct couplers 108. For example, the one or more duct couplers 108 may extend at an angle 120 from the bottom edge 110 of the first vertical duct 104 such that the width dimension 116 can be calculated as the length dimension 118 multiplied by the cosine of the angle 120. Furthermore, the value of the angle 120 may be based on the size difference between the first vertical duct 104 and the second vertical duct 106. For example, the first vertical duct 104 may have a first diameter 122 that is smaller than a second diameter 124 of the second vertical duct 106. That is, the second vertical duct 106 may be larger than the first vertical duct 104 such that one or more duct couplers 108 extend outward from the first vertical duct 104 at an angle 120 to couple the first vertical duct 104 to the second vertical duct 106. By way of example, the one or more duct couplers 108 may be formed from substantially planar fins with curved upper ends.

[0028] In some scenarios, one or more duct couplers 108 may be movable in response to actuation. For example, one or more duct couplers 108 may be hinged at one or more connection points 126 on the first vertical duct 104 and / or the second vertical duct 106. Additionally, one or more servo motors or other actuators may be coupled to one or more duct couplers 108 such that actuation in response to an electrical signal causes the one or more duct couplers 108 to rotate about their hinges. This may cause the first vertical duct 104 to rotate and / or move toward and / or away from the second vertical duct 106, which may change the direction of the resultant aerodynamic force, increasing and / or decreasing the width dimension 116 of the intake gap 114 in response to actuation and changing the direction of airflow relative to the vertical central axis, thereby creating a control moment on the AV center of gravity, which is typically along the vertical central axis. Additionally or alternatively, one or more duct couplers 108 may be self-retracting or detachable. As such, the AV 102 may be converted between a usable mode and a storage mode by detaching the first vertical duct 104 from the second vertical duct 106 and / or collapsing the AV 102. One or more duct couplers 108 may be detachable by threads, tongue and grooves, friction joints, or other actuatable mechanisms to separate the duct coupler 108 from the first vertical duct 104 and / or the second vertical duct 106 at one or more connection points 126. It should also be appreciated that in some examples, one or more duct couplers 108 may be statically and / or fixedly secured to the first vertical duct 104 and the second vertical duct 106 such that the width dimension 116 of the intake gap 114 does not change. Furthermore, one or more slide channels and / or other features formed in the first vertical duct 104 and / or the second vertical duct 106 may allow the second vertical duct 106 to rotate / pivot relative to the first vertical duct 104.

[0029] In some examples, the AV 102 may include a central post 128 extending along a central axis 130 of the AV 102. A propeller hub 132 may be disposed about the central axis 130, with one or more propeller blades 134 extending from the propeller hub 132 toward an inner surface of the first vertical duct 104 and / or the second vertical duct 106. For example, a first propeller 136 may be disposed within the first vertical duct 104, and a second propeller 138 may be disposed within the second vertical duct 106. Also, by making the second vertical duct 106 larger than the first vertical duct 104, the second propeller 138 may be larger (e.g., have a larger length and / or width dimension) than the first propeller 136. In some scenarios, the center post 128 and / or the propeller hub 132 can extend continuously through both the first vertical duct 104 and the second vertical duct 106 such that both the first propeller 136 and the second propeller 138 are attached to the propeller hub 132. In other scenarios, the center post 128 and / or the propeller hub 132 can be split with a space therebetween (e.g., aligned with the intake gap 114) such that the first propeller 136 is attached to a first hub segment in the first vertical duct 104 and the second propeller 138 is attached to a second hub segment in the second vertical duct 106.

[0030] In some scenarios, the first vertical duct 104 and / or the second vertical duct 106 can define an air path 140 through which an airflow 142 generated by one or more propeller blades 134 passes. The air path 140 can include a vertical component extending from a top opening 144 of the first vertical duct 104, through the first vertical duct 104, into a top opening 146 of the second vertical duct 106, and out a bottom opening 148 of the second vertical duct 106. For example, as shown in the cross-sectional view of FIG. 4A , the first vertical duct 104 can inhale air and direct the inhaled air downward into the duct 106. Furthermore, the air path 140 can include a lateral and / or horizontal component in that air can be simultaneously drawn into the intake gap 114 by one or more propeller blades 134 and pass through the second vertical duct 106 from a lower opening of the second vertical duct 106. 4(A), the lower duct 106 may also draw air from the side. Additionally or alternatively, the AV 102 may include one or more turbomachinery components (e.g., compressors, impellers, etc.) or gas turbines disposed within the first vertical duct 104 and / or the second vertical duct 106 to drive the airflow 142 through the airpath 140. As described in more detail below, the airflow 142 through the airpath 140 may be regulated and / or influenced by various features of the AV 102 to control the movement of the AV 102.

[0031] As mentioned above, the propulsion mechanism (such as, but not limited to, a propeller) can be driven by a motor connected to an aerodynamically neutral support, such as a stator, which can be aerodynamically neutral (zero air intake and symmetrical) or can serve the purpose of redirecting or straightening the flow. Any number of stators can be located above or below the propellers. One specific implementation of such a stator is shown in FIG. 5H, where a three-bladed stator 150 between the top and bottom propellers has a neutral aerodynamic effect (arranged to have a mean flow and shaped with a symmetrical airfoil shape) but also supports the motor and provides a streamlined enclosure for the wires connecting the motor to the battery (mounted on the top body). Additionally, a twelve-bladed bottom stator 152 provides turn correction to compensate for the higher torque of the bottom propeller, allowing the motor to achieve zero or near-zero torque in a hovering condition when operating at the designed rpm ratio. In this particular implementation, the bottom stator blades 152 cover the annular exit region but not the center section. Thus, in a hovering condition, the flow in the center region has a small swirl coming from the top propeller (which passed through the neutral stator 150 without swirl correction), with an associated torque that is offset by the swirl torque resulting from the bottom propeller and bottom stator 152 (which reduces, but does not eliminate, the swirl of the lower propeller). This particular implementation allows for yaw control by simply increasing the rotational speed of one of the motors (and optionally decreasing the rotational speed of the other motor to maintain the same lift). For example, a faster rotational speed of the top motor will result in a stronger swirl in the center region (from the top duct), causing the aircraft to yaw in the opposite direction. If the bottom motor is accelerated, the swirl in the outer annular region will be stronger, causing the aircraft to yaw in the opposite direction. In other implementations, stators 150 and 152 can be driven by actuators to tilt and generate torque or resultant forces to change the direction of airflow and / or induce swirl. For example, tilting the stators may change the direction of the aircraft during flight, adjusting the airflow around the stators, similar to controllable wings on an aircraft. The resulting change in airflow can direct the aircraft's movement accordingly.In other implementations, the stator blades 150 and 152 can be tilted so that yaw control can be achieved without changing the motor rpm. Finally, the stators 150 and 152 can also provide protection against the propeller (or any other propulsion system) when positioned above or below the top propeller (this particular implementation is used for illustrative purposes). In other implementations, one can take advantage of the aircraft's axisymmetric nature and include one or more cameras or other vision devices covering the full range from 0 to 360 degrees. In this case, yaw may be achieved electronically rather than mechanically, meaning the aircraft may be optimized for flight without mechanical yaw. In particular, the airflow may be aligned along an axis, with optimal rpms (relative to motor noise and power) and in a straight line without any turning. Electronic yaw can be achieved by switching between active cameras or by continuously composing all camera images in a panoramic 360-degree view.

[0032] 6A-6G illustrate an exemplary system 100 including an AV 102 having a first vertical duct 104 and / or a second vertical duct 106, which may be similar to or identical to and / or form part of the system 100 shown in FIGS. 5A-5G. FIG. 6A is a front view of the AV 102, FIG. 6B is a front perspective view of the AV 102, FIG. 6C is a bottom view of the AV 102, FIG. 6D is a top view of the AV 102, FIG. 6E is a left side view of the AV 102, FIG. 6F is a right side view of the AV 102, and FIG. 6G is a rear view of the AV 102.

[0033] 6A-6G, the AV 102 can include one or more navigation elements 202 that control the movement of the AV 102. The one or more navigation elements 202 can be one or more flaps 204 that are disposed around the second vertical duct 106. The flaps 204 can form extendable / retractable control surfaces (e.g., flat and / or curved) that can at least partially block or deflect the airflow 142 to control movement in a number of different mediums and spaces (e.g., on the ground and in the air). For example, the one or more flaps 204 can extend into the airpath 140 defined by the first vertical duct 104 and / or the second vertical duct 106 and at least partially change the direction of the airflow 142, generating a force that causes movement of the AV 102, rotation of the AV 102, or both. In some scenarios, four flaps 204, with link guides for pivotally attaching the flaps to the second vertical duct 106, can extend around the second vertical duct 106. The four flaps can also be spaced equidistantly apart. In some examples, 360° horizontal control is maintained by adjusting between different steering flap insertion configurations while providing propeller thrust to move the aircraft in a desired direction. A portion of the lift 206 generated by the propeller blades 134 can be converted into horizontal thrust 208 by the navigation member 202 at least partially blocking or deflecting the airflow 142 out the bottom of the second vertical duct 106. Movement of the flaps 204 can control the maneuvering of the AV 102 by changing the configuration that blocks or directs the airflow. These navigation members 202 may be moved by linkages 210 that connect the flaps 204 to the AV 102 (eg, to the sides and / or underside of the first vertical duct 104).

[0034] The disclosed flap-based control system can be used in an airborne transport mode and / or a ground transport mode using wheels that deploy from the bottom of the AV 102. For example, in a non-limiting example, the AV 102 includes two wheels at the rear and one wheel at the front to facilitate ground movement by redirecting lift 206 laterally to generate horizontal movement. Other versions may have four wheels, two at the rear and two at the front. The wheels can also be arranged to help the AV 102 tilt forward or backward and move forward or backward. Omnidirectional wheels can also ensure movement in any direction and facilitate rotation around a vertical axis (such as perpendicular to the ground). Other versions can have one or more steerable front wheels that rotate freely to facilitate rotation around a vertical axis. In some versions, only two wheels can be used, and flaps can maintain balance and control movement. It will be understood that any number, type, and / or configuration of wheels can be used. Several other ground interface components may be used to ensure reduced ground friction, allowing the aircraft to easily move over different surfaces, including, but not limited to, omnidirectional wheels and / or low-friction pads. Any of these mechanisms, including the wheels, may be permanently fixed, removable, retractable, and / or the like. In some cases, these mechanisms may be motorized to allow for remote deployment and / or retraction of the wheels and / or pads (e.g., similar to an aircraft's landing gear) and / or manual deployment and / or retraction by a human. The wheels may also be removable via mechanical magnetic locks. The wheels may also be equipped with mechanisms that allow for quicker stopping and braking to prevent the aircraft from moving unintentionally. In some cases, the wheels may be retractable to prevent unintentional movement and / or reduce air resistance in airborne transport mode.Once the AV102 lands within a predetermined proximity of the destination location, the wheel and flap navigation system may be used to navigate the AV102 to the destination location, such as a charging dock, other power source, and / or data upload location. Additionally or alternatively, the AV102 may include other surface contacts, such as treads, track attachments, rollers, low friction running surfaces, and combinations thereof.

[0035] This configuration can be beneficial when operating indoors or in other settings where the AV102 can advantageously maneuver on flat surfaces and fly over obstacles and stairs. For example, the AV102 may transition to ground transport mode when inspecting complex duct work and piping that is difficult to access and where stable flight is not possible due to recirculating air that causes turbulence. The ability to operate in a different transport mode can be useful when high-precision landings (such as on a charging station) are required, as the AV102 can land close to the charging station and ensure accurate final positioning.

[0036] In some examples, the second vertical duct 106 may include one or more receiving areas, such as a spigot 212, slot, or cavity, for receiving or at least partially receiving the flap 204. For example, the outer surface 214 of the second vertical duct 106 may have a plurality of notches having a shape corresponding to the shape of the flap 204. Additionally, the second vertical duct 106 may include one or more sliding portions, such as slots and / or grooves, that facilitate sliding movement of the flap 204 under and / or into the airflow 142 at the bottom opening of the second vertical duct 106. The movement of the flap 204 into and / or out of the airflow 142 may also include at least partial movement toward and / or away from the central axis 130 of the AV 102.

[0037] In some examples, the flap 204 may be positioned at other locations on the AV 102. For example, the flap 204 may be located along the inner surface 216 of the second vertical duct 106 and / or may be contained within an interior space of the second vertical duct 106 (e.g., between the outer surface 214 and the inner surface 216). Furthermore, the flap 204 may be disposed in the first vertical duct 104 and / or configured to at least partially block the intake gap 114. The AV 102 may have the flap 204 in multiple different locations or any combination of the disclosed locations. Furthermore, in some scenarios, one or more of the navigation members 202 may include other types of mechanisms, such as an opening (e.g., formed in the second vertical duct 106) that can be controllably opened and closed, a hinged portion of the second vertical duct 106, or any other mechanism that can vary and / or block the airflow 142 through the second vertical duct 106 and / or the first vertical duct 104.

[0038] Additionally, the AV 102 may include a housing 218 that may be at least partially formed around the first vertical duct 104. The housing 218 may include a shell 220 that at least partially encloses internal components of the AV 102, such as a control system 222. The control system 222 may include computing components and / or software for performing various disclosed operations. For example, a non-transitory memory storage device may store computer-readable instructions that, when executed by one or more processors, cause the AV 102 to perform steering and / or navigation operations. This may include actuating one or more navigation members 202 by moving the link 210 and / or changing the propeller rotational speed. The control system 222 may also control any lighting operations, camera operations, microphone operations, and / or wireless communication transmissions (e.g., using a cellular network interface and / or other wireless interface) performed by the AV 102. Any of these components (e.g., camera, microphone, power supply, transceiver, linkage actuators, etc.) may be at least partially housed within housing 218, along with wiring for connecting these internal components to control system 222. The navigation control operations performed by control system 222 are described in more detail below with respect to Figures 8 and 9.

[0039] In some examples, the shell 220 of the housing 218, the first vertical duct 104, the second vertical duct 106, the one or more duct couplers 108, the one or more navigation members 202, and / or any other externally exposed components of the AV 102 may have contours that improve the airflow 142 and / or the overall aerodynamics of the AV 102. For example, the housing 218 and / or the first vertical duct 104 enclosed by the housing 218 may have a generally rounded ring shape 224 with a tapered lower portion 226. The tapered lower portion 226 may be formed by the housing 218 and / or the first vertical duct 104 having a shape that transitions from a convex curve to a concave curve before terminating at the intake gap 114. Furthermore, in some scenarios, portions of the AV 102, such as the first vertical duct 104 and the second vertical duct 106, may be shaped to act as wings. For example, the AV 102 may be able to rotate in pitch or roll so that the airflow 142 transitions from a vertical configuration to a horizontal configuration. In the horizontal configuration, the ducts 104 and 106 can act similarly to fixed wings when the AV 102 is traveling at least partially horizontally, generating a significant portion of the lift required for flight. FIG. 7 illustrates such an example in cross-section of the AV 102, showing the body wall designed to generate a significant portion of the lift when the AV is flying forward, reducing power requirements from the motor and increasing efficiency. In this case, the body duct or wall 226 acts similarly to a conventional wing on an airplane. One or more navigation members 202 of the AV 102 can still be used to perform maneuvers (such as moving up, down, left, and / or right) when the AV 102 is in the horizontal configuration. Also, in other configurations, lift for forward flight can be partially generated by additional aerodynamic surfaces, such as wings. The wings are either fixed or extended during forward flight and retracted when the aircraft is primarily hovering or landing, i.e., in horizontal flight, where multiple ducts with their respective drive mechanisms and flow paths can be part of a larger system to provide the thrust required to maintain forward speed.

[0040] FIG. 8 illustrates an exemplary system 100 including an AV 102 having a first vertical duct 104 and / or a second vertical duct 106, which may be similar to, identical to, and / or form part of the system 100 illustrated in FIGS. 5A-6G.

[0041] 8 , the AV 102 can use the flaps 204 to perform one or more maneuvers 302. The one or more maneuvers 302 can include flight maneuvers when the AV 102 is airborne (e.g., “air mode”) and / or steering / driving maneuvers when the AV 102 is traveling on a surface and / or ground via wheels 303 (e.g., “ground mode”). The one or more maneuvers 302 can include extending the first flap 304 and / or the second flap 306 to generate a thrust component 208 from the airflow 142 passing through the bottom opening of the second vertical duct 106. Additionally or alternatively, the one or more maneuvers 302 can include changing and / or maintaining the height of the AV 102 by extending all of the one or more navigation members 202 to change the lift component 206. The one or more maneuvers 302 can further include a rotational maneuver. Additionally, the one or more maneuvers 302 may include altering the rotational speed of one or more propeller blades 134 in conjunction with or as an alternative to extending and / or retracting the flaps 204 .

[0042] In some examples, one or more maneuvers 302 can be caused and / or controlled by a control system 222 executing various software steps. For example, flap insertion may be adjusted by the control system 222 using the following equation:

[0043]

number

[0044] where x may be a flap index, Ix may be the flap insertion amount for flap x, γ may be a control magnitude calculated by a control algorithm in the control system 222, which may take into account sensor measurements and the desired position, angle, acceleration, and velocity, etc., α may be an angle corresponding to the direction of the desired thrust vector, δx may be the angular offset of each flap 204 from the forward direction of the aircraft, F(α+δx) may be the relative flap insertion required to generate a thrust vector in the direction α, and i start can be an initial flap insertion between 0 and 1. In some cases, flaps 204 can be initiated with a non-zero value. This occurs when a small flap insertion does not result in significant thrust vectoring. In such cases, i start The parameter may allow storing the flap 204 positioned in the opposite direction of α.

[0045] In some examples, each of the multiple flaps 204 can use the same function F. Using the same function F can take into account the relative position of each of the flaps. The following offsets can be used for the four flaps to operate the AV 102:

[0046] [Table 1]

[0047] In some scenarios, the control system 222 may implement a nonlinear function to maximize control over a certain region of the airflow 142 and account for the effect of having more than one flap 204 extended at a certain point. In some iterations, the flaps 204 may start at a non-zero position, for example, when the thrust vector amount is not substantially sufficient for small flap insertion. In such cases, the flaps 204 may still be fully retracted to the zero position, but only after the opposite flap is fully inserted. These techniques may provide more precise control in the desired direction along the x- and y-axes.

[0048] In some examples, the first flap 304 and the second flap 306 are positioned to vector the thrust toward 0°. start While in the 45° position, the third flap 308 and the fourth flap can be inserted by equal amounts. To angle the thrust towards 45°, the second flap 306, the third flap 308, and the fourth flap are inserted by equal amounts while the first flap 304 is in the 45° position. start To angle the thrust to 67.5°, the first flap 304 is inserted by an equal amount while in the start While in position , the second and third flaps 306 and 308 can be inserted equally while the fourth flap is inserted less than the second and third flaps 306 and 308. In this example, start is 0.

[0049] In some examples, the AV 102 may use different flap insertion configurations for thrust vectoring in air transport mode versus ground transport mode. For example, in flight, the third and fourth flaps 308 and 306 may be extended to navigate at a 0° heading. On the ground, the first and second flaps 304 and 306 may instead be extended to navigate at a 0° heading. That is, transitioning between different modes of operation may include reversing the direction of the thrust vector. The first flap insertion configuration for the air transport mode may be the opposite and / or inverted shape of the second flap insertion configuration for the ground transport mode. In some examples, associating direction with the flap insertion amount / shape is a computationally efficient way to control the direction of the aircraft, allowing the control system to maintain and / or change directional control of the aircraft using minimal resources.

[0050] In some examples, the control of each of the flaps 204 can vary depending on the speed of each of the propellers and the resulting thrust magnitude. To compensate for this, the flap insertion equation may include an additional term.

[0051]

number

[0052] where T represents the amount of thrust generated by the propeller. Alternatively, the individual speeds of each of the motors can be used in place of thrust. In this case, the formula can include:

[0053]

number

[0054] where P1 is the speed of the first propeller and P2 is the speed of the second propeller. In some cases, the control amount is dictated solely or predominantly by the bottom propeller.

[0055] In some instances, the pitch-up moment can be compensated for by modifying flap insertion, which changes the amount of torque generated by the flaps to counter the pitch-up moment. One or all of speed and / or heading can be used to calculate the corrected flap insertion. In this case, the formula for calculating flap insertion becomes:

[0056]

number

[0057] where Ω is a vector of Euler angles indicating the aircraft's current direction, and ν is a vector of aircraft velocity.

[0058] FIG. 9 illustrates an example method 400 for controlling an AV 102 that may form and / or be implemented at least in part in one or more of the disclosed systems 100.

[0059] In some examples, in a first operation 402, the method 400 can provide at least a first portion of lift to the aircraft by rotating a first propeller disposed in the first vertical duct. In operation 404, the method 400 can provide at least a second portion of lift to the aircraft by rotating a second propeller disposed in the second vertical duct, positioned below the first vertical duct, and coaxially aligned with the first vertical duct. In operation 406, the method 400 can move one or more flaps disposed in the second vertical duct to create a change in airflow through an airpath defined by the first vertical duct coaxially aligned with the second vertical duct.

[0060] As described above, creating a change in airflow affects the lift component, and the aircraft can be steered based on the change to the airflow that affects the lift component. In one implementation, one or more of the first vertical duct 104 and / or the second vertical duct 106 may be movable or actuated relative to the opposing duct to generate a moment to steer the AV. For example, FIG. 10(A) is a cross-sectional view of an AV in which the second duct 106 is horizontally displaced from the first duct 104. The second duct 106 can be oriented into the illustrated configuration by actuating the second duct to an offset position. FIG. 10(B) illustrates the displacement of the second duct 106 out of alignment with the first duct 104, including an additional degree of freedom (i.e., tilt angle displacement in addition to horizontal displacement). The second duct 106 can be oriented into this configuration by one or more additional actuators. In this manner, actuation of one or more actuators may displace the first duct 104 and / or the second duct 106 to generate thrust displacements in a plane (as shown in FIG. 10(A)) or at an oblique angle (as shown in FIG. 10(B)). The actuators may also move the first duct 104 and / or the second duct 106 vertically relative to one another to collapse the ducts into a stowed mode or increase the distance between the ducts for a flight mode. In general, the ducts of an AV may be oriented and / or moved in any configuration via actuation of one or more actuators of the AV.

[0061] In some examples, an AV may include a body portion made up of interchangeable modular sections that can be easily modified for different purposes or uses of the AV. For example, one such module may have additional cameras or electronics, another module may provide additional energy storage (such as a battery pack), or another module may carry chemicals or fuel. Depending on the goals of a given particular mission, the payload may be easily selected by switching between one or more of these sections.

[0062] In other possible implementations, the body of the upper duct and / or bottom duct may have walls built with multiple thin films of metal and / or dielectric material that provide structural strength and electrical energy storage, i.e., the walls of the body shell may be configured to operate as supercapacitor devices, taking advantage of the enormous volume and available area compared to conventional quad drones or other aircraft.

[0063] The volume available within the enclosure 218 can be used to carry passengers for urban transportation in some examples. Passenger seats may self-tilt to maintain a comfortable position as the aircraft changes flight angle to maintain optimal performance. In this configuration, the AV can take off and land vertically within a confined space while maintaining performance with the available airflow area.

[0064] The described implementations provide various configurations and optimizations for the AV. For example, portions of the AV may be detachable for storage and reattachable for operation. Different modules may be used to form ducts for the AV and inserted into the ducts to provide various flight behaviors. Additionally, some implementations may include ducts, such as the bottom duct, with a shape configurable to react to wind gusts, creating corrective moments to compensate for wind gusts that may tilt the AV during flight. Thus, the AV may experience wind gusts, and the shape of the duct may be adjusted in response to the wind gusts.

[0065] In other implementations, at least one of the AV's payload areas may include a mechanism, such as a ramp or automated arm, that provides for delivery of items or cargo. In other examples, the AV may retrieve items or cargo from the payload area. Such cargo delivery may occur after landing or while hovering near the ground. The payload area may also be used to transport passengers. In such examples, the seats may optionally tilt according to the flight angle to provide comfort during flight.

[0066] Optimization of one or more components of the AV may also be included in some designs. For example, one or more stators or diffusers of the AV may be used to provide support for the motor, environmental protection, enclosures for wiring or fuel supplies (from the battery or fuel tank to the motor or engine), and / or enclosures for the transmission shaft. Such stators may be used to render the AV aerodynamically neutral or as a means of redirecting airflow. Yaw control of the AV may be achieved by varying the rotational speed (rpm) of the propeller and / or by varying at least a portion of the stator blade angle. Portions of the duct walls may be constructed in a manner that provides dual functionality, i.e., structural strength and energy storage, via layers of metal or metal oxide that form embedded batteries or supercapacitors. Some implementations of the AV may also include extending wings that extend when flying forward at a near-horizontal pitch angle, or the thrust systems of larger fixed-wing aircraft.

[0067] The various thrust vectoring mechanisms disclosed can be applied to any aircraft that uses thrust vectoring. While the technology of this disclosure has been described with reference to various implementations, it will be understood that these implementations are exemplary and that the scope of the technology of this disclosure is not limited thereto. Many variations, modifications, additions, and improvements are possible. More generally, implementations according to the technology of this disclosure have been described in the context of specific implementations. Functionality may be separated differently or described with different terms in various implementations of the disclosure. These and other variations, modifications, additions, and improvements may be included within the scope of the disclosure, as defined by the following claims.

Claims

1. An aircraft, a first duct defining at least a first portion of a lift-generating air path; a second duct perpendicularly offset from the first duct and defining at least a second portion of the air path; one or more propulsion devices disposed within the airpath to capture the shape of the airflow downstream of the aircraft for thrust and control of the aircraft; An aircraft comprising:

2. 2. The aircraft of claim 1, further comprising one or more flaps coupled to the second duct and movable between different positions to influence the airflow and thereby control movement of the aircraft.

3. 2. The aircraft of claim 1, wherein the first duct has a first diameter and the second duct has a second diameter different from the first diameter.

4. 10. The aircraft of claim 1, further comprising one or more hinged duct couplers connecting the first duct to the second duct and operable to move the second duct relative to the first duct.

5. The aircraft of claim 1 , wherein the one or more propulsion devices comprise a propeller, a rotor, a turbomachinery component, or a gas-fired jet.

6. 10. The aircraft of claim 1, wherein at least one of the first duct and the second duct has an annular shape and generates lift during level flight of the aircraft.

7. 10. The aircraft of claim 1, further comprising one or more removable sections that reduce the footprint for storage of the aircraft and allow the first duct and the second duct to be configured.

8. 10. The aircraft of claim 1, further comprising a first propeller driving a central portion of the airpath, and a second propeller configured to have an aerodynamically neutral shape.

9. 9. The aircraft of claim 8, further comprising: a downstream propeller receiving airflow from a secondary portion of the airpath different from the central portion, the secondary portion of the airpath receiving the airpath through a secondary intake area.

10. The aircraft of claim 1 , wherein the one or more propulsion devices comprises a plurality of propulsion devices, each operating at a different speed.

11. An aircraft, a first duct defining at least a first portion of the air path; a second duct disposed below and collinear with the first duct, the second duct defining at least a second portion of the air path; one or more propulsion devices disposed within the second duct and drawing air through at least an intake gap defined between the first duct and the second duct; one or more movable navigation members joined to the second duct for controlling movement of the aircraft; An aircraft comprising:

12. 12. The aircraft of claim 11, wherein the one or more movable navigation members include a plurality of wheels that deploy from the second duct to operate the aircraft as a terrain vehicle.

13. 12. The aircraft of claim 11, further comprising a plurality of duct couplers extending between the first duct and the second duct.

14. 12. The aircraft of claim 11, wherein the one or more propulsion devices include a first propeller disposed in the first duct and a second propeller disposed in the second duct.

15. 12. The aircraft of claim 11, including one or more actuators that extend at least one of the one or more movable navigation members into the airpath, thereby causing the aircraft to perform a piloting movement.

16. generating at least a first portion of lift for the aircraft by rotating a first propeller disposed within the first vertical duct; generating at least a second portion of the lift by rotating a second propeller disposed in a second vertical duct below the first vertical duct and coaxially aligned with the first vertical duct; changing an air flow through an air path defined by the first vertical duct arranged coaxially with the second vertical duct by movement of one or more flaps disposed on the second vertical duct; 1. A method for controlling the movement of an aircraft, comprising:

17. 17. The method of claim 16, wherein creating a change in the airflow affects a lift component, and the aircraft is maneuvered based on the change to the airflow that affects the lift component.

18. 17. The method of claim 16, wherein rotating the second propeller includes drawing air through an intake gap between the first vertical duct and the second vertical duct.

19. 17. The method of claim 16, further comprising actuating one or more duct couplers to move the first vertical duct relative to the second vertical duct as part of a flight maneuver.

20. 17. The method of claim 16, further comprising actuating one or more duct couplers to collapse the aircraft into a storage mode.

Images